Rotary drill bit



May 22, 1962 A. F. PICKARD ETAL ROTARY DRILL BIT Filed Feb. 27, 1959Kar/ c/. H/apka United States Patent 3,035,647 ROTARY DRILL BIT AlbertF. Pickard, Karl J. Klapka, and Leo Catallo, Detroit, Mich., assignorsto Wheel Trueing Tool Company, Detroit, Mich., a corporation of DelawareFiled Feb. 27, 1959, Ser. No. 796,124 6 Claims. (Cl. 175-387) Thisinvention relates to rotary drill bits and more particularly relates toa rotary drill bit adapted to cut large diameter shallow holes orrecesses, in rock, concrete, or the like.

It is often desirable to cut shallow but relatively large diameter holesin very hard surfaces such as concrete and the like for such purposes ascutting light-receiving sockets for landing lights in a concreteairplane runway. It has in the past, however, been found ditficult toprevent large diameter drill bits from slipping along the surface to becut as the cutting operation is being initiated.

In order to obviate the difficulties involved in cutting large diameterholes in concrete or the like with ordinary drill bits, we have deviseda drill bit which has a relatively small diameter abrasive annulusformed centrally of a substantially flat abrading face and protrudingfrom the abrading face. This abrasive annulus initially contacts andcuts into the surface to be drilled to thereby cut a small groove inthat surface prior to contact of the large diameter fiat abrading facetherewith.

The abrasive member has a plurality of particle collection areas orcountersinks formed therein which are communicable through suitablechannels with the periphery of the drill bit and which are adapted to besupplied with pressurized fluid from a central bore formed within thedrill bit to wash fine particles and sludge from the bit.

The abrasive member is removably connected with a mounting member by aplurality of bolts or other suitable securing means which are disposedwithin the respective eountersinks in the abrasive member so as to bereadily accessible to permit removal of the abrasive member from themounting member as desired.

The rotary drill bit which is illustrated in the drawings also has anannular abrading ring formed about the periphery of the drill bit whichis adapted to form a water collection trap in the material being drilledabout the periphery of the drilled hole but the central abrading ringprotrudes from the substantially flat surface of the abrading face adistance greater than the peripheral abrading ringso that the centralabrading ring bites the surface of the material to be drilled prior tocontact of the outer abrading ring therewith. In this manner, slippageof the drill bit over the material to be drilled is prevented and thedrill bit is readily steadied in its proper position during theoperation thereof.

A central bore is formed in the abrasive member which is communicablewith a source of pressurized fluid and which is also communicable witheach of the several countersinks to provide a means for properly coolingthe abrading head of the drill bit and to also provide a means forflushing the drilled particles from the path of movement of the abradingface of the drill bit. While the provision of such a bore in the drillbit leaves an upstanding core in the drilled hole, the core isrelatively short and of small diameter and may be readily chipped awayafter the drilling operation.

It is important to note that the bore formed within the mounting memberis diametrically smaller than the coaxially aligned bore formed withinthe abrasive member so that a shoulder is formed on the mounting memberintermediate the radially enlarged and radially reduced bores which isadapted to abut the central core remaining in the drilled hole. Uponcontact of the core with this shoulder, the drill bit is prevented frommoving deeper ice into the material to be drilled so that holes ofconstant depth may readily be drilled. Obviously, the depth of the holeto be drilled will be determined by the distance intermediate theshoulder defining the radially reduced bore within the mounting memberand the abrading face of the abrasive member.

Accordingly, it is a principal object of the present invention toprovide a rotary drill bit which is not subject to slippage or travelover the surface to be drilled upon the initiation of the drillingoperation.

Another object of the invention is to provide a two-part drill bitcomprising a mounting and an abrasive member in which ready access maybe had to the securing means interconnecting the members with oneanother.

A further object of the invention is to provide a drill bit of the typeabove described having a means for adequately cooling the abrasivesurface of the bit and for flushing foreign particles from the bit.

Yet another object of the present invention is to provide a drill bitwhich is not subject to slippage upon initiation of the drillingoperation which has a simple and eflicient means for drilling holes ofconstant depth.

These and other objects of the invention will become apparent from timeto time as the following specification proceeds and with reference tothe accompanying drawings, wherein:

FIGURE 1 is a plan view of the abrading face of a drill bit constructedin accordance with the principles of the present invention; and

FIGURE 2 is a vertical sectional view through the bit illustrated inFIGURE 1 which is taken along lines II-II of FIGURE 1.

As shown in the drawings, a drill bit 10 comprises generally a mountingmember 11 and an abrasive member 12 which are connected together bymeans of a plurality of cooperating nuts and bolts 13 which extendthrough coaxially aligned apertures 14 in the respective members.

The mounting member 11 has a bore 15 formed centrally therein which isthreaded as at 16 to be secured to the barrel of a drilling machine. Theabrasive member 12 has a bore 17 formed, centrally therein disposed inregistry with the bore 15 and has an annular flange 18 formed integrallytherewith and extending upwardly therefrom which is adapted to seatwithin a central recess 19 in the mounting member 11.

An abrasive face 20 having a plurality of diamonds or other suitableabrasives secured therein is provided on the lower surface of theabrasive member 12 following the contours thereof and extending upwardlyalong the outer edge thereof and into the bore 17 as an integral part ofsaid member 12.

An annulus or bead 21 is formed about the outer periphery of theabrasive member 12 and is arranged to form a groove 21a in the concrete22 during the drilling operation to provide a well for containing anyfluid seeping into the hole 22a drilled by the bit 10 about theperiphery thereof.

A second annular ring or head 23 is formed radially inwardly of the ring21 coaxially with the bore 17 and extends axially downwardly of thesubstantially fiat abrading face 20 of the abrading member 12 a greaterdistance than the annular ring 21 so that when the drilling operation isbegun the annular ring 23 will contact and cut the concrete prior to thecontact of the annular ring 21 therewith.

It is to be noted that the ring 23 has a diameter less than half that ofthe face 20 and that due to the relatively small contact area of thering 23 with the concrete the bit may readily be steadied and preventedfrom slipping by the operator thereof and the annular ring 23 will actas a guide or pilot to initially cut into the surface of the concreteprior to movement of the entire abrading surface into contact therewith.

As shown in the drawings, the annular bead 23 tapers downwardly at thesides to present downwardly convergent side cutting surfaces. The crosssection of the bead in the preferred illustrated form is rounded orarcuate. The bead will first engage the surface of the concrete in linecontact. As soon as the bead starts cutting, the line contact willbroaden as the surfaces on each side of the bead cut down into theconcrete. The bead will cut a rounded depression in the concrete, withthe curved sides of the depression facing upwardly and laterally towardthe bead preventing lateral displacement. The bead is thus at all timesduring the cutting action always cutting fresh concrete with its lateralsurfaces thus insuring the absence of lateral shifting.

As shown most clearly in FIGURE 1, a plurality of wells or countersinks25 are formed within the substantially flat face 20 of the bit 10. Theface 20 is also cut out as at 26 to provide a means for communicatingpressurized fluid from the coaxially aligned bores and 17 to therespective wells 25. Assuming that the bit 10 is arranged forcounterclockwise rotatable movement as viewed in FIGURE 1, a pluralityof passages 27 are formed through the abrasive face 20 by cutting outportions of the face 20 which extend in a clockwise direction from eachof the wells and which terminate at the periphery of the abrasive member12.

The face 20 is also cut out as at 28 through the annular ring 21 topermit fluid flow from the wells 25 to the periphery of the abrasivemember 12.

Fluid pumped at high pressure through the coaxially aligned bores 15 and17, in the manner which is Well known in the art, will flow through thepassages 26 into the Wells 25 where it will collect the relatively fineparticles cut in the concrete by the bit 10 and will flush the same outthrough the passages 27 and 28 to the periphery of the bit 10.

Applicants have thus provided a drill bit for drilling large diametershallow holes in hard surfaces such as concrete or the like which mayreadily be prevented from slipping over the surface to be drilled duringthe drilling operation and which may readily be guided by the operatorthereof. In addition the invention is directed to a means for coolingand flushing the abrading surfaces of the drill bit.

It will be understood that this embodiment of the pres ent invention hasbeen used for illustrative purposes only and that other features,modifications, and variations in the present invention may be effectedwithout departing from the spirit and scope of the novel conceptsthereof.

Weclaim as our invention:

1. A rotary drill bit having a substantially flat abrading face, anannular abrading ring formed about the periphery of said bit andprotruding from said abrading face, and a second abrading ringprotruding from said abrading face a greater distance than said firstmentioned abrading ring and centrally thereof having a diameter lessthan onehalf that of said abrading face.

2. A rotary drill bit having a substantially flat abrading face, anannular ring formed about the periphery of said bit and protruding fromsaid abrading face, a plurality of countersinks formed in said abradingface and opening to the periphery thereof through said annular ring, anda second abrading ring protruding from said abrading face a greaterdistance than said first mentioned abrading ring and centrally of saidabrading face having a diameter less than one-half that of said abradingface.

3. A rotary drill bit having a substantially fiat abrading face, anannular ring formed about the periphery of said bit and protruding fromsaid abrading face, a plurality of countersinks formed in said abradingface and opening to the periphery thereof through said abrading ring,radially inwardly disposed fluid flow passages opening to each of saidcountersinks, and a second abrading ring protruding from said abradingface centrally thereof a greater distance than said first mentionedabrading ring having a diameter less than one-half that of said abradingface.

4. A rotary drill bit having a substantially flat abrading face, aplurality of countersinks formed in said abrading face, a bore formedcentrally within said bit and opening to said countersinks, passagewaymeans leading from said countersinks to the periphery of said abradingface along a chord line of said abrading face so arranged that fluiddisposed Within said countersinks will be directed therethrough duringrotation of said bit, and an abrading ring protruding from said abradingface centrally thereof having a diameter less than one-half that of saidabrading face.

5. A rotary drill bit comprising a mounting member and an abradingmember mounted on said mounting member, a substantially flat abradingface formed in said abrading member, an annular ring formed about theperiphery of said abrading member, bores formed centrally within each ofsaid members and disposed in registry with one another, a plurality ofcountersinks formed in said abrading face, means communicating said borewithin said abrading member with each of said countersinks, passagewaymeans leading from said countersinks to the periphery of said abradingmember so arranged that fluid disposed within said countersinks will bedirected therethrough during rotation of said bit, securing meansdisposed within said countersinks and extending through each of saidmembers for securing said members to one another, and an abrading ringprotruding from said abrading face centrally thereof a greater distancethan said annular ring and having a diameter less than one-half that ofsaid abrading face.

6. A rotary drill bit comprising a mounting member and an abradingmember mounted on said mounting member, a substantially flat abradingface formed in said abrading member, an annular ring formed about theperiphery of said abrading member, bores formed centrally within each ofsaid members and disposed in registry with one another, a plurality ofcountersinks formed in said abrading face, passageway means leading fromsaid countersinks to the periphery of said abrading member along a chordline of said abrading member so arranged that fluid disposed within saidcountersinks will be directed therethrough during rotation of said bit,securing means disposed within said countersinks and extending througheach of said members for securing said members to one another, and anabrading ring protruding from said abrading face centrally thereof agreater distance than said annular ring and having a diameter less thanone-half that of said abrading face, the bore within said abradingmember being diametrically greater than the bore within said mountingmember.

References Cited in the file of this patent UNITED STATES PATENTS137,435 Gillespie Apr. 1, 1873 1,088,452 Rist et al. Feb. 24, 19141,413,471 Goerner Apr. 18, 1922 1,805,678 Smith May 19, 1931 2,053,801Mitchell Sept. 8, 1936 2,371,488 Williams Mar. 13, 1945 2,545,195 CrakeMar. 13, 1951 2,729,427 Davis et al Jan. 3, 1956 2,819,043 HendersonJan. 7. 1958

